CN113929644B - Propylene oxide purification and propylene glycol co-production method - Google Patents
Propylene oxide purification and propylene glycol co-production method Download PDFInfo
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- C07C29/103—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of ethers, including cyclic ethers, e.g. oxiranes of cyclic ethers
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- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
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Abstract
The application relates to a method for purifying propylene oxide and co-producing propylene glycol, which comprises the following steps: the first material flow enters from the lower part of the extraction tower, deionized water (second material flow) enters from the upper part of the extraction tower, the third material flow is obtained at the top of the tower, and the fourth material flow is obtained at the bottom of the tower; the fourth material flow enters a propylene glycol recovery tower, deionized water (fifth material flow) enters from the upper part of the propylene glycol recovery tower, a sixth material flow is obtained at the top of the tower, and a seventh material flow is obtained at the bottom of the tower; the seventh material flow is sent into a propylene glycol product tower, a propylene glycol product (twelfth material flow) is obtained by side line extraction, and the eighth material flow is mainly dipropylene glycol and heavy components in the tower bottom. The method can be used in industrial production of propylene oxide purification and propylene glycol recovery.
Description
Technical Field
The application relates to a method for purifying propylene oxide and co-producing propylene glycol.
Background
Propylene Oxide (PO) is the second largest propylene derivative other than polypropylene and is an important basic organic chemical synthesis raw material. The largest industrial application of propylene oxide is in the preparation of polyether polyols, and also in propylene glycol, fourth-generation detergent nonionic surfactants, oilfield demulsifiers, pesticide emulsifiers, wetting agents, and the like. Propylene oxide derivatives are widely used in the industries of automobiles, buildings, foods, tobacco, medicines, cosmetics and the like. The produced downstream products are nearly hundreds of kinds, and are important raw materials of fine chemical products.
Propylene Oxide (PO) was first produced in 1931 by the traditional process of chlorohydrination by united states carbon company, and subsequently produced by chlorohydrination by DOW and BASF in the united states, respectively, in 1942 and 1948. At present, the production process of PO mainly comprises four types: chlorohydrin method, co-oxidation method (co-oxidation method for co-producing styrene, PO/SM method for short and co-oxidation method for co-producing tertiary butanol, PO/TBA method for short), hydrogen peroxide direct oxidation method (HPPO method) and cumene oxidation method (CHP method). Currently, the four processes for PO production account for 43.2%, 48.2%, 4.9% and 3.7% of global capacity, respectively. In the co-oxidation method, the PO/SM co-oxidation method was 32.7%, and the PO/TBA co-oxidation method was 15.5%. The PO/TBA process faces major problems as MTBE is increasingly being banned worldwide. At present, development of PO production technology mainly focuses on the aspects of green and environment-friendly new process development, improvement of traditional PO production technology and the like.
Because of the influence of technical reasons, most of the PO devices in China are produced by a chlorohydrination method at present, only Zhonghai oil-Shell and Zhenhai refining-Lyondell are produced by a PO/SM co-oxidation method, zhongpetrochemical long-period petrochemical industry is produced by adopting an HPPO technology with independent intellectual property rights of Zhongpetrochemical industry (Dan Keyuan), the CHP method technology independently developed by China petrochemical Shanghai petrochemical institute of petrochemical industry is about to be applied to Tianjin petrochemical industry, and epoxybutane is about to be applied to Yanshan petrochemical industry.
In the propylene oxide purification process, because propylene oxide and methanol form an azeotrope, the method has no report (US 5849938; CN108912071; simulation and optimization of the mixture of propylene oxide and methanol by extraction and rectification, [ J ] modern chemical industry, 2012,32 (5): 114-116; hu Song, li Jinlong, yang Weisheng. The tail gas methanol absorption and purification process of propylene oxide [ J ] chemical engineering, 2020,71 (4): 1667-1675) adopts water as an extractant to separate methanol contained in crude propylene oxide, and the aim of well removing methanol and purifying propylene oxide can be achieved as a result, but the method has no report above that the water is used as the extractant, the propylene oxide inevitably generates hydrolysis reaction to generate 1, 2-propylene glycol (propylene glycol for short), the propylene glycol also generates dipropylene glycol (dipropylene glycol for short), the generation amount of the dipropylene glycol and the polytrimethylene glycol is about 10% of that of the propylene glycol, and the propylene glycol is used as a heavy component for removing after treatment such as an incinerator, and the resource utilization rate is reduced. The application can reduce the hydrolysis amount of propylene oxide, and simultaneously recover propylene glycol generated by hydrolysis to reach the national standard of propylene glycol products, and can be used as products for sale, or can co-produce 1, 2-propylene glycol according to the propylene glycol demand by arranging a catalyst in a rectifying tower.
Disclosure of Invention
Propylene oxide has active property and is easy to open-loop polymerization, and can react with various solvents such as water, ammonia, alcohol, carbon dioxide and the like to generate corresponding compounds or polymers. The application aims at the technical problems that in the propylene oxide purification process, water is adopted as an extractant, propylene oxide inevitably generates side reactions to generate propylene glycol, dipropylene glycol, glycol polymer, propylene oxide and glycol polymer, the operation temperature is unreasonably controlled, the side reactions such as coking and the like occur at the tower bottom, and the propylene glycol is not recycled and is discharged as heavy components. The application provides a method for purifying propylene oxide and co-producing propylene glycol, which solves the technical problems and comprises the following steps:
a) Comprises water, propylene oxide, methanol, formaldehyde+acetaldehyde, propionaldehyde and C 5 ～C 6 A first stream of hydrocarbon, benzene, ethylbenzene or isopropylbenzene, 1, 2-propanediol and dipropylene glycol is fed from below the extraction tower, deionized water (second stream) is fed from above the extraction tower, and a third stream is obtained from the top of the extraction tower (C is separated by a subsequent separation process) 5 ～C 6 Obtaining propylene oxide products after hydrocarbons), and obtaining a fourth material flow from the tower kettle;
b) The fourth material flow mainly comprises propylene glycol, water, methanol and heavy hydrocarbons such as ethylbenzene or isopropylbenzene, the propylene glycol enters a propylene glycol recovery tower, deionized water (fifth material flow) enters from the upper part of the propylene glycol recovery tower, a sixth material flow is obtained at the top of the tower, and a seventh material flow is obtained at the bottom of the tower;
c) And the seventh material flow is sent into a propylene glycol product tower, residual water (ninth material flow) and ethylbenzene or isopropylbenzene (tenth material flow) are removed by azeotropic distillation by using ethylbenzene or isopropylbenzene as an entrainer at the tower top, a propylene glycol product (twelfth material flow) is obtained by side line extraction, and the eighth material flow is mainly dipropylene glycol and heavy components at the tower bottom.
The adding amount of the extractant water directly determines the methanol content in the crude propylene oxide at the top of the extraction tower, the mass ratio of the second stream to the first stream is too low, the methanol content in the propylene oxide exceeds the standard, excessive hydrolysis loss of propylene oxide is caused if the mass ratio of the second stream to the first stream is not controlled to be 1:20-5:20.
The extraction tower top is crude propylene oxide with the mass fraction purity exceeding 98%, and the pressure is too low, so that the temperature of a cooling medium of a tower top condenser is low, such as chilled water, and the public engineering cost is increased; meanwhile, the tower bottom contains components such as propylene glycol, dipropylene glycol and the like, and the temperature of the tower bottom is not too high, so that the operating pressure is controlled to be 0.02-0.10 MPaG, and the operating temperature is controlled to be 30-60 ℃. Under the condition that the extraction tower is not filled with a solid catalyst, propylene oxide can also react with water in a non-catalytic hydration way to generate 1, 2-propanediol, dipropylene glycol and polytrimethylene glycol. The propylene glycol, the dipropylene glycol and the polytrimethylene glycol are directly taken as heavy components to be collected and burned, the resource utilization rate is low, and if an effective mode is adopted, the device economy can be improved by recycling the propylene glycol.
Both the extraction column and the propylene glycol recovery column may be packed with solid catalyst and packing, preferably the latter packed with catalyst.
In order to ensure that the content of methanol and water in the epoxypropane at the top of the extraction tower meets the product requirement, a small part of epoxypropane is pressed at the tower kettle, so that the tower kettle contains a small amount of epoxypropane, the content of epoxypropane in the tower kettle can be controlled according to the market demand, and the propylene oxide content directly determines the propylene glycol yield of the device. Adding a strand of deionized water into the upper part of the propylene glycol recovery tower, filling a solid catalyst and a filler between the two feeds, enabling propylene oxide and water entering the propylene glycol recovery tower to undergo a catalytic reaction, converting the propylene oxide into propylene glycol, and separating and recovering the propylene oxide from the tower kettle. The propylene oxide hydrolysis reaction is exothermic, and the reaction occurs in the rectifying tower, so that the reaction heat can be fully utilized, and the heat load of a reboiler of the rectifying tower can be reduced. Propylene oxide is hydrolyzed to generate propylene glycol, and the main reaction heat is 69.6kJ/mol.
The fifth stream molar flow rate of the propylene glycol recovery column and the propylene oxide molar flow rate of the fourth stream are (1.5:1) - (5.0:1).
The tower bottom mainly comprises propylene glycol, dipropylene glycol and heavy components, the operating pressure is 20-60 kPaA, and the operating temperature of the tower bottom is not more than 170 ℃.
In order to reduce the reaction occurrence rate of propylene glycol, dipropylene glycol, and the like in polymerization at high temperature, the pressure of the propylene glycol recovery tower is reduced, the separation process is beneficial, and a filler is preferably used between the fourth material flow and the tower kettle to reduce the pressure drop of the rectifying tower, thereby reducing the temperature of the tower kettle.
The theoretical plate number of the propylene glycol product tower is 25-40, and the lateral line extraction position is 10-15 plates above the feeding position. In order to improve the purity of propylene glycol and reduce the dipropylene glycol content in the propylene glycol product, the side offtake material of the propylene glycol product tower is cooled to 35-45 ℃.
After the side offtake material of the propylene glycol product tower is cooled, a part of the side offtake material is taken as propylene glycol product, a part of the side offtake material is taken as reflux, the reflux ratio is 1-3, and the reflux return position is 1-2 plates below the side offtake position.
Because the propylene glycol product tower from which the propylene glycol recovery tower bottom liquid is extracted contains a small amount of heavy hydrocarbons such as ethylbenzene or cumene, and is required to be separated and discharged from the tower top, the propylene glycol product tower top forms a low-boiling azeotrope by utilizing cumene or ethylbenzene impurities and water, and a third medium is not introduced as an entrainer. The phase separation after condensing the tower top gas is not to adopt the organic phase after condensing the tower top gas phase condensate phase separation as reflux liquid directly, because the organic phase contains trace metal ions and poly PO, PO-glycol polymers though liquid-liquid phase separation, the chromaticity of propylene glycol products is affected, therefore, part of the organic phase is used as reflux liquid for circularly separating residual water after washing by deionized water, part of the water phase is extracted, and the water phase is completely extracted for post treatment. In order to reduce the water content in the propylene glycol product, azeotropic distillation is adopted for water separation.
At least part of the organic phase is used as reflux liquid after the phase separation of the gas phase condensate at the top of the propylene glycol product, and the organic phase is preferably washed by deionized water.
When condensate is directly adopted as reflux liquid at the top of the propylene glycol product, the chromaticity of the side-stream extracted propylene glycol product (7) can not meet the quality requirement of the superior product.
Because the propylene glycol, the dipropylene glycol and the heavy components are heat-sensitive substances, the excessive temperature can lead to polymerization and coking of products, unqualified product quality, blockage of equipment such as a reboiler and the like, the operation pressure of a propylene glycol product tower is 1-10 kPaA, and the operation temperature of a tower kettle is not more than 195 ℃.
Because dipropylene glycol and heavy components in the tower bottom are heat-sensitive substances, the viscosity is high, and the vaporization rate of reboiling liquid in the propylene glycol product tower is not more than 6 percent.
The application has the following advantages: (1) Adding deionized water into a propylene glycol recovery tower, carrying out reactive distillation to produce propylene glycol, reducing propylene oxide loss, and recovering propylene glycol; (2) The propylene glycol product tower uses ethylbenzene or isopropylbenzene as an entrainer to remove residual water by azeotropic distillation; (3) Propylene glycol product is extracted from the side line, and the number of separation equipment is reduced. (4) The high recovery rate of propylene glycol is realized by combining the process flows, and the recovery rate is more than 99.3 percent, preferably more than 99.5 percent.
The application is also applicable to alkylene oxide systems such as butylene oxide.
Drawings
FIG. 1 is a schematic flow chart of the method of the present application.
Reference numerals illustrate:
a extraction tower
B propylene glycol recovery tower
C propylene glycol product tower
1. First stream, crude PO feed stream
2. Second stream, deionized water
3. A third stream, an extraction column A overhead stream
4. Fourth material flow, extraction tower A kettle extract material flow
5. Fifth material flow, deionized water
6. Sixth stream, propylene glycol recovery column B top extract stream
7. Seventh stream, propylene glycol recovery column B kettle extract stream
8. Eighth material flow, propylene glycol product tower C kettle extract material flow
9. Ninth stream, propylene glycol product column C top aqueous phase extract stream
10. Tenth stream, propylene glycol product column C top organic phase extract stream
11. Eleventh stream, propylene glycol product column C overhead organic phase reflux stream
12. Eleventh stream, propylene glycol product column C side draw stream
A first material flow (1) of crude propylene oxide enters from the lower part of a first material flow extraction tower A, a second material flow deionized water (2) enters from the upper part of the extraction tower, a third material flow (3) is obtained at the top of the tower, and C is separated by a subsequent separation process 5 ～C 6 Obtaining propylene oxide products after hydrocarbons, and obtaining a fourth material flow (4) at the tower kettle, wherein the fourth material flow mainly contains propylene glycol, dipropylene glycol, water, propylene oxide and heavy hydrocarbons such as ethylbenzene or isopropylbenzene;
the fourth material flow (4) is sent to a propylene glycol recovery tower B, the fifth material flow (5) is added from the upper part of the tower, the top of the tower is extracted to form a sixth material flow (6), and the bottom of the tower is extracted to form a seventh material flow (7);
and (3) removing propylene glycol from the seventh stream (7), washing a part (11) of the organic phase after phase separation of the gas phase condensate at the top of the tower by deionized water, circularly separating residual water as reflux liquid, directly extracting part (10), and completely extracting and post-treating the water phase (9). The side stream is separated into two parts after being extracted and cooled, one part is taken as an extracted twelfth stream (12), the other part is taken as a side stream reflux, the twelfth stream is propylene glycol product, the tower bottom is taken as an eighth stream, and the eighth stream is propylene glycol, propylene glycol and heavy components.
The application is described in detail below with reference to the attached drawings, but it should be noted that the scope of the application is not limited thereto but is defined by the appended claims.
All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, definitions, will control.
When the specification derives materials, substances, methods, steps, devices, or elements and the like in the word "known to those skilled in the art", "prior art", or the like, such derived objects encompass those conventionally used in the art as the application suggests, but also include those which are not currently commonly used but which would become known in the art to be suitable for similar purposes.
In the context of this specification, any matters or matters not mentioned are directly applicable to those known in the art without modification except as explicitly stated. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or ideas thus formed are all deemed to be part of the original disclosure or original description of the present application, and should not be deemed to be a new matter which has not been disclosed or contemplated herein, unless such combination is clearly unreasonable by those skilled in the art.
Unless explicitly indicated, all percentages, parts, ratios, etc. mentioned in this specification are by weight unless otherwise clear to the routine knowledge of a person skilled in the art.
The application is further illustrated by the following detailed description.
Detailed Description
[ example 1 ]
A first material flow (1) of crude propylene oxide enters from the lower part of a first material flow extraction tower A, a second material flow deionized water (2) enters from the upper part of the extraction tower, a third material flow (3) is obtained at the top of the tower, and C is separated by a subsequent separation process 5 ～C 6 Obtaining propylene oxide products after hydrocarbons, and obtaining a fourth material flow (4) at the tower kettle, wherein the fourth material flow mainly contains propylene glycol, dipropylene glycol, water, propylene oxide and heavy hydrocarbons such as ethylbenzene or isopropylbenzene;
the fourth material flow (4) is sent to a propylene glycol recovery tower B, the fifth material flow (5) is added from the upper part of the tower, the top of the tower is extracted to form a sixth material flow (6), and the bottom of the tower is extracted to form a seventh material flow (7);
and (3) removing propylene glycol from the seventh stream (7), washing a part (11) of the organic phase after phase separation of the gas phase condensate at the top of the tower by deionized water, circularly separating residual water as reflux liquid, directly extracting part (10), and completely extracting and post-treating the water phase (9). The side stream is separated into two parts after being extracted and cooled, one part is taken as an extracted twelfth stream (12), the other part is taken as a side stream reflux, the twelfth stream is propylene glycol product, the tower bottom is taken as an eighth stream, and the eighth stream is propylene glycol, propylene glycol and heavy components.
The first stream (1) contains water, propylene oxide, methanol, formaldehyde+acetaldehyde, propionaldehyde, C 5 ～C 6 The mass compositions of hydrocarbons, benzene, ethylbenzene, 1, 2-propylene glycol and dipropylene glycol are 0.9671%, 98.6475%, 0.0967%, 0.0009%, 0.0309%, 0.0619%, 0.1180%, 0.0130%, 0.0582% and 0.0056% in sequence.
The mass ratio of the second stream to the first stream is controlled at 1.05:20, the operating pressure of the extraction tower A is 0.022MPaG, and the operating temperature is 40 ℃.
The mass flow ratio of propylene oxide in the fourth stream to that in the first stream was 4.5:100.
The fifth stream molar flow rate and the fourth stream molar flow rate of propylene oxide in propylene glycol recovery column B were 1.52:1.
The propylene glycol recovery column B was operated at 20kPaA, 60℃and 145℃at the bottom of the column.
And a packing is used between the fourth material flow and the tower kettle to reduce the pressure drop of the rectifying tower, thereby reducing the temperature of the tower kettle.
The theoretical plate number of the propylene glycol product tower is 25, and in order to improve the purity of propylene glycol and reduce the dipropylene glycol content in the propylene glycol product, the side line extraction position of the propylene glycol product tower is 10 plates above the feeding position.
Because the propylene glycol, the dipropylene glycol and the heavy components are all heat-sensitive substances, the excessive temperature can lead to the propylene glycol product tower operating pressure of 2kPaA, and the tower kettle operating temperature is not more than 180 ℃.
The vaporization rate of the reboiling liquid of the propylene glycol product tower is 3.8 percent.
The side offtake of the propylene glycol product column is cooled to 36 ℃.
After the side offtake material of the propylene glycol product tower is cooled, a part of the side offtake material is taken as propylene glycol product, a part of the side offtake material is taken as reflux, the reflux ratio is 1.25, and the reflux return position is 1 plate below the side offtake position.
Propylene glycol product tower kettle temperature is 180 ℃.
The third stream (3) contains propylene oxide, formaldehyde+acetaldehyde, C 5 ～C 6 The hydrocarbon comprises 99.9348%, 0.0009% and 0.0632% of the mass composition in sequence. After the C8 hydrocarbon is used as an extractant for extraction and rectification (not included in the application), the propylene oxide product, propylene oxide, formaldehyde+acetaldehyde and C which are superior products can be obtained 5 ～C 6 The hydrocarbon comprises 99.9980%, 0.0010% and 0.0010% of the total mass.
The twelfth stream (12) contains 1, 2-propanediol, water, dipropylene glycol, and the mass composition is 99.8552%, 0.1398%, and 0.0050% in this order. The recovery rate of 1, 2-propanediol was 99.65%.
[ example 2 ]
The same as in example 1, except that the first stream (1) is water, propylene oxide, methanol, formaldehyde + acetaldehyde, propionaldehyde, C 5 ～C 6 Hydrocarbon, benzene, ethylbenzene, 1, 2-propylene glycol and dipropylene glycol, and the mass composition thereof is 1.0000%, 98.6450%, 0.0900%, 0.0010%, 0.0200%, 0.0600%, 0.1100%, 0.0100%, 0.0590% and 0.0070% in this order.
The mass ratio of the second stream to the first stream was controlled at 1.53:20, the operating pressure of extraction column A was 0.035MPaG, and the operating temperature was 43 ℃.
The mass flow ratio of propylene oxide in the fourth stream to that in the first stream was 3.52:100.
The fifth stream molar flow rate and the fourth stream molar flow rate of propylene oxide in propylene glycol recovery column B were 2:1.
The propylene glycol recovery column B was operated at 25kPaA, 65℃and the column bottoms at 150 ℃.
And a packing is used between the fourth material flow and the tower kettle to reduce the pressure drop of the rectifying tower, thereby reducing the temperature of the tower kettle.
The theoretical plate number of the propylene glycol product tower is 28, and in order to improve the purity of propylene glycol and reduce the dipropylene glycol content in the propylene glycol product, the side line extraction position of the propylene glycol product tower is 11 plates above the feeding position.
Because propylene glycol, dipropylene glycol and heavy components are all heat-sensitive substances, an excessively high temperature can lead to the propylene glycol product tower operating pressure of 3kPaA and the tower kettle operating temperature of 181 ℃.
The vaporization rate of the reboiling liquid of the propylene glycol product tower is 4.2 percent.
The side offtake of the propylene glycol product column was cooled to 39 ℃.
After the side offtake material of the propylene glycol product tower is cooled, a part of the side offtake material is taken as propylene glycol product, a part of the side offtake material is taken as reflux, the reflux ratio is 1.42, and the reflux return position is 1 plate below the side offtake position.
Propylene glycol product tower kettle temperature is 182 ℃.
The third stream (3) contains propylene oxide, formaldehyde+acetaldehyde, C 5 ～C 6 The hydrocarbon comprises 99.9370%, 0.0010% and 0.0620% by mass. After the C8 hydrocarbon is used as an extractant for extraction and rectification (not included in the application), the propylene oxide product, propylene oxide, formaldehyde+acetaldehyde and C which are superior products can be obtained 5 ～C 6 The hydrocarbon comprises 99.9981%, 0.0010% and 0.0009% by mass.
The seventh stream (7) contains 1, 2-propanediol, water, dipropylene glycol, and the mass composition is 99.8562%, 0.1397%, 0.0041% in this order. The recovery of 1, 2-propanediol was 99.62%.
[ example 3 ]
The same as in example 1, except that the first stream (1) is water, propylene oxide, methanol, formaldehyde + acetaldehyde, propionaldehyde, C 5 ～C 6 The mass compositions of the hydrocarbons, benzene, ethylbenzene, 1, 2-propylene glycol and dipropylene glycol are 1.0500%, 98.5560%, 0.1050%, 0.0009%, 0.0300%, 0.0500%, 0.1200%, 0.0090%, 0.0750% and 0.0070% in sequence.
The mass ratio of the second stream to the first stream was controlled at 2.05:20, the operating pressure of extraction column A was 0.045MPaG, and the operating temperature was 45 ℃.
The mass flow ratio of propylene oxide in the fourth stream to that in the first stream was 3.05:100.
The fifth stream molar flow rate and the fourth stream molar flow rate of propylene oxide in propylene glycol recovery column B were 2.5:1.
The propylene glycol recovery column B was operated at a pressure of 35kPaA, an operating temperature of 72℃and a column bottom operating temperature of 158 ℃.
And a packing is used between the fourth material flow and the tower kettle to reduce the pressure drop of the rectifying tower, thereby reducing the temperature of the tower kettle.
The theoretical plate number of the propylene glycol product tower is 30, and in order to improve the purity of propylene glycol and reduce the dipropylene glycol content in the propylene glycol product, the side line extraction position of the propylene glycol product tower is 11 plates above the feeding position.
Because propylene glycol, dipropylene glycol and heavy components are all heat-sensitive substances, an excessively high temperature can lead to the propylene glycol product tower operating pressure of 4kPaA and the tower kettle operating temperature of 182 ℃.
The vaporization rate of the reboiling liquid of the propylene glycol product tower is 4.5 percent.
The side offtake of propylene glycol product column is cooled to 40 ℃.
After the side offtake material of the propylene glycol product tower is cooled, a part of the side offtake material is taken as propylene glycol product, a part of the side offtake material is taken as reflux, the reflux ratio is 1.52, and the reflux return position is 1 plate below the side offtake position.
Propylene glycol product tower kettle temperature 183 ℃.
The third stream (3) contains propylene oxide, formaldehyde+acetaldehyde, C 5 ～C 6 The hydrocarbon comprises 99.9480%, 0.0010% and 0.0510% of the total mass. After the C8 hydrocarbon is used as an extractant for extraction and rectification (not included in the application), the propylene oxide product, propylene oxide, formaldehyde+acetaldehyde and C which are superior products can be obtained 5 ～C 6 The hydrocarbon comprises 99.9982%, 0.0010% and 0.0008% of the total mass of the catalyst.
The seventh stream (7) contains 1, 2-propanediol, water, dipropylene glycol, and the mass composition is 99.8569%, 0.1392%, 0.0039% in this order. The recovery rate of 1, 2-propanediol was 99.60%.
[ example 4 ]
The same as in example 1, except that the first stream (1) is water, propylene oxide, methanol, formaldehyde + acetaldehyde, propionaldehyde, C 5 ～C 6 Hydrocarbons, benzene, ethylbenzene, 1The mass compositions of the 2-propylene glycol and the dipropylene glycol are 0.9510%, 98.6930%, 0.0790%, 0.0008%, 0.0250%, 0.0500%, 0.1000%, 0.0180%, 0.0750% and 0.0078% in sequence.
The mass ratio of the second stream to the first stream was controlled at 2.08:20, the operating pressure of extraction column A was 0.055MPaG, and the operating temperature was 47 ℃.
The mass flow ratio of propylene oxide in the fourth stream to that in the first stream was 2.53:100.
The fifth stream molar flow rate and the fourth stream molar flow rate of propylene oxide in propylene glycol recovery column B were 3.04:1.
The propylene glycol recovery column B was operated at 45kPaA, 78℃and the column bottoms at 166 ℃.
And a packing is used between the fourth material flow and the tower kettle to reduce the pressure drop of the rectifying tower, thereby reducing the temperature of the tower kettle.
The theoretical plate number of the propylene glycol product tower is 32, and in order to improve the purity of propylene glycol and reduce the dipropylene glycol content in the propylene glycol product, the side line extraction position of the propylene glycol product tower is 11 plates above the feeding position.
Because propylene glycol, dipropylene glycol and heavy components are all heat-sensitive substances, an excessively high temperature can lead to the propylene glycol product tower operating pressure of 5kPaA and the tower kettle operating temperature of 185 ℃.
The vaporization rate of the reboiling liquid of the propylene glycol product tower is 4.5 percent.
The propylene glycol product column side offtake was cooled to 38 ℃.
After the side offtake material of the propylene glycol product tower is cooled, a part of the side offtake material is taken as propylene glycol product, a part of the side offtake material is taken as reflux, the reflux ratio is 1.45, and the reflux return position is 1 plate below the side offtake position.
Propylene glycol product tower kettle temperature 183 ℃.
The third stream (3) contains propylene oxide, formaldehyde+acetaldehyde, C 5 ～C 6 The hydrocarbon comprises 99.9460%, 0.0010% and 0.0530% of the total mass. After the C8 hydrocarbon is used as an extractant for extraction and rectification (not included in the application), the propylene oxide product, propylene oxide, formaldehyde+acetaldehyde and C which are superior products can be obtained 5 ～C 6 The hydrocarbon comprises 99.9980%, 0.0010% and 0.0010% of the total mass.
The seventh stream (7) contains 1, 2-propanediol, water, dipropylene glycol, and the mass composition is 99.8562%, 0.1399%, 0.0039% in this order. The recovery rate of 1, 2-propanediol was 99.60%.
[ example 5 ]
The same as in example 1, except that the first stream (1) is water, propylene oxide, methanol, formaldehyde + acetaldehyde, propionaldehyde, C 5 ～C 6 The mass composition of hydrocarbon, benzene, isopropylbenzene, 1, 2-propylene glycol and dipropylene glycol is 0.630%, 98.9830%, 0.0850%, 0.0010%, 0.0260%, 0.0600%, 0.1299%, 0.0090%, 0.0700% and 0.0062% in sequence.
The mass ratio of the second stream to the first stream is controlled at 3.06:20, the operating pressure of the extraction tower A is 0.070MPaG, and the operating temperature is 50 ℃.
The mass flow ratio of propylene oxide in the fourth stream to that in the first stream was 1.05:100.
The fifth stream molar flow rate and the fourth stream molar flow rate of propylene oxide in propylene glycol recovery column B were 4.08:1.
The propylene glycol recovery column B was operated at a pressure of 52kPaA, an operating temperature of 82℃and a column bottom operating temperature of 170 ℃.
And a packing is used between the fourth material flow and the tower kettle to reduce the pressure drop of the rectifying tower, thereby reducing the temperature of the tower kettle.
The theoretical plate number of the propylene glycol product tower is 35, and in order to improve the purity of propylene glycol and reduce the dipropylene glycol content in the propylene glycol product, the side line extraction position of the propylene glycol product tower is 12 plates above the feeding position.
Because propylene glycol, dipropylene glycol and heavy components are all heat-sensitive substances, an excessively high temperature can lead to a propylene glycol product tower operating pressure of 6kPaA and a tower kettle operating temperature of 187 ℃.
The vaporization rate of the reboiling liquid of the propylene glycol product tower is 5.0 percent.
The side offtake of propylene glycol product column is cooled to 40 ℃.
After the side offtake material of the propylene glycol product tower is cooled, a part of the side offtake material is taken as propylene glycol product, a part of the side offtake material is taken as reflux, the reflux ratio is 1.80, and the reflux return position is 2 plates below the side offtake position.
Propylene glycol product column bottom temperature 185 ℃.
The third stream (3) contains propylene oxide, formaldehyde+acetaldehyde, C 5 ～C 6 The hydrocarbon comprises 99.9458%, 0.0010% and 0.0532% by mass. After the C8 hydrocarbon is used as an extractant for extraction and rectification (not included in the application), the propylene oxide product, propylene oxide, formaldehyde+acetaldehyde and C which are superior products can be obtained 5 ～C 6 The hydrocarbon comprises 99.9980%, 0.0010% and 0.0010% of the total mass.
The seventh stream (7) contains 1, 2-propanediol, water, dipropylene glycol, and the mass composition is 99.8570%, 0.1390%, 0.0040% in this order. The recovery rate of 1, 2-propanediol was 99.56%.
[ example 6 ]
The same as in example 1, except that the first stream (1) is water, propylene oxide, methanol, formaldehyde + acetaldehyde, propionaldehyde, C 5 ～C 6 The mass compositions of the hydrocarbon, benzene, isopropylbenzene, 1, 2-propylene glycol and dipropylene glycol are 0.5900%, 99.0170%, 0.0600%, 0.0010%, 0.0260%, 0.0460%, 0.1600%, 0.0120%, 0.0800% and 0.0076% in sequence.
The mass ratio of the second stream to the first stream was controlled at 4.10:20, the operating pressure of extraction column A was 0.081MPaG, and the operating temperature was 52 ℃.
The mass flow ratio of propylene oxide in the fourth stream to that in the first stream was 4.08:100.
The fifth stream molar flow rate and the fourth stream molar flow rate of propylene oxide in propylene glycol recovery column B were 5.10:1.
The propylene glycol recovery column B was operated at a pressure of 65kPaA, an operating temperature of 87.6℃and a column bottom operating temperature of 177 ℃.
And a packing is used between the fourth material flow and the tower kettle to reduce the pressure drop of the rectifying tower, thereby reducing the temperature of the tower kettle.
The theoretical plate number of the propylene glycol product tower is 38, and in order to improve the purity of propylene glycol and reduce the dipropylene glycol content in the propylene glycol product, the side line extraction position of the propylene glycol product tower is 14 plates above the feeding position.
Because propylene glycol, dipropylene glycol and heavy components are all heat-sensitive substances, an excessively high temperature can lead to a propylene glycol product tower operating pressure of 9kPaA and a tower kettle operating temperature of 190 ℃.
The vaporization rate of the reboiling liquid of the propylene glycol product tower is 6.0 percent.
The propylene glycol product column side offtake was cooled to 43 ℃.
After the side offtake material of the propylene glycol product tower is cooled, a part of the side offtake material is taken as propylene glycol product, a part of the side offtake material is taken as reflux, the reflux ratio is 2.55, and the reflux return position is 2 plates below the side offtake position.
Propylene glycol product tower kettle temperature is 192 ℃.
The third stream (3) contains propylene oxide, formaldehyde+acetaldehyde, C 5 ～C 6 The hydrocarbon comprises 99.9490%, 0.0010% and 0.0500% of the total mass. After the C8 hydrocarbon is used as an extractant for extraction and rectification (not included in the application), the propylene oxide product, propylene oxide, formaldehyde+acetaldehyde and C which are superior products can be obtained 5 ～C 6 The hydrocarbon comprises 99.9983%, 0.0010% and 0.0007% by mass.
The seventh stream (7) contains 1, 2-propanediol, water, dipropylene glycol, and the mass composition is 99.8615%, 0.1345%, 0.0040% in this order. The recovery of 1, 2-propanediol was 99.52%.
[ example 7 ]
Unlike example 1, the mass ratio of the second stream to the first stream was controlled at 4.5:20, the propylene oxide yield was reduced by 0.50%, and the 1, 2-propanediol yield was increased by 0.41%.
[ example 8 ]
Unlike example 1, the propylene glycol recovery column B bottoms operating temperature was 185 ℃, the propylene glycol product bottoms temperature was 205 ℃, the propylene glycol yield was reduced by 0.20%, and the bottoms reboiler coking rate was increased.
Claims (11)
1. A method for purifying propylene oxide and co-producing propylene glycol, comprising the steps of:
a) First stream comprising crude propylene oxide is extracted fromTaking the lower part of the tower, taking deionized water from the upper part of the extraction tower, obtaining a third material flow containing propylene oxide, formaldehyde and acetaldehyde at the top of the tower, obtaining a fourth material flow at the bottom of the tower, and separating C by the third material flow through a subsequent separation process 5 ~C 6 Obtaining propylene oxide products after hydrocarbons;
b) A fourth stream containing propylene glycol, water, methanol and heavy hydrocarbons enters a propylene glycol recovery tower, deionized water enters the propylene glycol recovery tower from the upper part of the propylene glycol recovery tower, a sixth stream containing light components is obtained at the top of the tower, and a seventh stream is obtained at the bottom of the tower;
c) The seventh material flow is sent into a propylene glycol product tower, ethylbenzene or isopropylbenzene is taken as an entrainer to enter from the top of the tower, residual water and ethylbenzene or isopropylbenzene are removed by azeotropic distillation, a propylene glycol product is obtained by side stream extraction, and an eighth material flow containing dipropylene glycol and heavy components is arranged at the bottom of the tower;
the molar flow rate of deionized water in the propylene glycol recovery tower and the molar flow rate of propylene oxide in the fourth stream are (1.5:1) - (5.0:1);
the first stream comprises water, propylene oxide, methanol, formaldehyde+acetaldehyde, propionaldehyde, C 5 ~C 6 Hydrocarbons, benzene, ethylbenzene or cumene, 1, 2-propanediol, dipropylene glycol;
the operation pressure of the propylene glycol recovery tower is 20-60 kPaA, and the operation temperature of a tower kettle is not more than 175 ℃;
the operation pressure of the propylene glycol product tower is 1-10 kPaA, and the operation temperature of the tower kettle is not more than 200 ℃.
2. The propylene oxide purification and co-production process of claim 1, wherein the heavy hydrocarbons in the fourth stream comprise ethylbenzene or cumene.
3. The method for purifying propylene oxide and co-producing propylene glycol as defined in claim 1, wherein the light component in said sixth stream comprises methanol.
4. The method for purifying propylene oxide and co-producing propylene glycol according to claim 1, wherein in the step a), the mass ratio of deionized water to the first stream is 1:20 to 5:20.
5. The method for purifying propylene oxide and co-producing propylene glycol according to claim 1, wherein the extraction column has an operating pressure of 0.02-0.10 mpa g and an operating temperature of 30-60 ℃.
6. The method for purifying propylene oxide and co-producing propylene glycol according to claim 1, wherein the extraction column and the propylene glycol recovery column are both packed with a solid catalyst and a packing.
7. The method for purifying propylene oxide and co-producing propylene glycol as defined in claim 6, wherein said propylene glycol recovery column is packed with a catalyst.
8. The method for purifying propylene oxide and co-producing propylene glycol according to claim 1, wherein a packing is used between the fourth stream of the propylene glycol recovery column and the column bottoms.
9. The method for purifying propylene oxide and co-producing propylene glycol according to claim 1, wherein the propylene glycol product has a theoretical plate number of 25 to 40.
10. The method for purifying propylene oxide and co-producing propylene glycol according to claim 1, wherein the side offtake position of the propylene glycol product tower is 8-12 theoretical plates above the feed.
11. The method for purifying propylene oxide and co-producing propylene glycol according to claim 1, wherein a part of the organic phase is directly extracted after phase separation of the gas phase condensate at the top of the propylene glycol product, and a part of the organic phase is used as reflux liquid after washing with deionized water.
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| CN101693703A (en) * | 2009-10-14 | 2010-04-14 | 大连理工大学 | Energy-saving and emission-reducing technique for producing propane epoxide by using hydrogen peroxide epoxidation propylene |
| CN103788026A (en) * | 2012-10-29 | 2014-05-14 | 中国石油化工股份有限公司 | Method of purifying propylene epoxide |
| CN105712953A (en) * | 2016-01-26 | 2016-06-29 | 江苏怡达化学股份有限公司 | Method of pre-purifying epoxy propane |
| CN109851583A (en) * | 2017-11-30 | 2019-06-07 | 中国石油化工股份有限公司 | Epoxyalkane purification process |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101693703A (en) * | 2009-10-14 | 2010-04-14 | 大连理工大学 | Energy-saving and emission-reducing technique for producing propane epoxide by using hydrogen peroxide epoxidation propylene |
| CN103788026A (en) * | 2012-10-29 | 2014-05-14 | 中国石油化工股份有限公司 | Method of purifying propylene epoxide |
| CN105712953A (en) * | 2016-01-26 | 2016-06-29 | 江苏怡达化学股份有限公司 | Method of pre-purifying epoxy propane |
| CN109851583A (en) * | 2017-11-30 | 2019-06-07 | 中国石油化工股份有限公司 | Epoxyalkane purification process |
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